Peeling solution for photo- or electron beam-sensitive resin and process for peeling off said resin

ABSTRACT

The peeling solution for photo- or electron beam-sensitive resin according to the present invention consists of an aqueous solution comprising hydrogen peroxide and a compound represented by the general formula (I) ##STR1## wherein R 1  is H or an alkyl group of 1-2 carbon atoms, R 2  is H or an alkyl group of 1-3 carbon atoms, and R 3  is H or an alkyl group of 1-3 carbon atoms. 
     The process for peeling off a photo- or electron beam-sensitive resin according to the present invention comprises a step of treating a photo- or electron beam-sensitive resin-coated substrate with a peeling solution for photo- or electron beam-sensitive resin cnsisting of an aqueous solution comprising hydrogen peroxide and a compound represented by the above general formula (I).

This is a division of application Ser. No. 07/314,961, filed Feb. 24,1989 now U.S. Pat. No. 5,037,724.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to a peeling solution for photo- orelectron beam-sensitive resin and to a process for peeling off a photo-or electron beam-sensitive resin using said solution. The presentinvention is applied for removing a photo- or electron beam-sensitiveresin from a substrate.

(2) Description of the Prior Art

As substrates on which a photo- or electron beam-sensitive resin is tobe coated, there are, for example, those composed of glass, metal,plastic or ceramic, as well as those consisting of a glass and a thinfilm (made of a metal or the like) formed thereon. On a case of using,as such a substrate, a photomask blank (hereinafter may be referred tosimply as "blank") which is used as a material for photomask in theproduction of semiconductor integrated circuits (e.g. IC, LSI), thereare explained below the conventional peeling slutions for photo- orelectron beam-sensitive resin and the conventional processes for peelingoff a photo- or electron beam-sensitive resin.

The above mentioned blank consists of a light-transmitting substrate(e.g. polished silica glass) and a light-shielding film (e.g. chromiumfilm) formed on one main surface of the substrate. In producing aphotomask from the blank, firstly a photo- or electron beam-sensitiveresin such as photoresist, electron beam resist or the like is coated onthe light-shielding film of the blank by a coating method such as spincoating or the like.

In the above coating of a photo- or electron beam-sensitive resin on thelight-shielding film, it occurs at times that the film of the photo- orelectron beam-sensitive resin formed on the light-shielding film of theblank has non-uniform thickness depending upon the resin coatingconditions (e.g. temperature) and the resin properties (e.g. viscosity).When such a blank on which a photo- or electron beam-sensitive resinfilm has been formed in non-uniform thickness is then subjected to aphotolithography step or an electron beam lithography step to produce aphotomask, the light-shielding pattern formed on the light-transmittingsubstrate has no constant line width as required and it is impossible toobtain a photomask having a desired light-shielding pattern.

The blank on which a photo- or electron beam-sensitive resin film hasbeen formed in non-uniform thickness is regarded as a blank with aresist of unacceptable film thickness and cannot be used practically.However, when such a blank with a resist of unacceptable film thicknessis made of an expensive light- transmitting substrate such as silicaglass or the like, the light-transmitting substrate is reutilized byimmersing the blank in a peeling solution for photo- or electronbeam-sensitive resin to peel off the photo- or electron beam-sensitiveresin (the resist) and then peeling off and removing the light-shieldingfilm with a given etching solution. The resulting light-transmittingsubstrate is repolished and then provided with a new light-shieldingfilm to produce a blank; and a photo- or electron beam-sensitive resinis coated on the light-shielding film.

As the peeling solution used when the photo- or electron beam-sensitiveresin to be peeled off thereby is a photoresist sensitive to a lightsuch as ultraviolet light or the like, there has been known thefollowing peeling solutions, that is, a photoresist peeling solutionconsisting of a mixture of an aqueous hydrogen peroxide and sulfamicacid (Japanese Patent Application Kokai (Laid-Open) No. 13776/1977), aphotoresist film remover consisting of a mixture obtained by adding anacid to a persulfate, hydrogen peroxide or a hydrogen peroxide adduct(Japanese Patent Application Kokai (Laid-Open) No. 24627/1979), and aphotoresist peeling solution consisting of a mixture of acetone andN,N-dimethylformamide (Japanese Patent Publication No. 6101/1982).

The photo- or electron beam-sensitive resin to be peeled off includes,besides the above mentioned photoresists, electron beam resistssensitive to electron beam, and the electron beam resists include thoseof negative type and those of positive type. The electron beam resistsof negative type include, for example, an epoxy resin, an unsaturateddicarboxylic acid resin and a polystyrene, and the electron beam ofpositive type include, for example, a polyolefinsulfone and a polymethylmethacrylate.

As the peeling solution for these electron beam resists, there are knownmethyl ethyl ketone, hot concentrated sulfuric acid, dimethyl sulfoxide,methylene chloride, etc.

With the above conventional peeling solutions for photoresist or evenwith the above conventional peeling solutions for electron beam resist,it is difficult to peel off electron beam resists reliably in a shorttime.

Therefore, a very long time is required when a blank whoselight-transmitting substrate is to be reutilized is immersed in aconventional peeling solution for electron beam resist to peel off theelectron beam resist and then is treated with a given etching solutionto remove the light-shielding film. It is because a very thin resistsfilm remains on the light-shielding film at the time of the peeling ofthe electron beam resist owing to the strong adhesion of the resist tothe light-shielding film and hinders the removal of the light-shieldingfilm.

Meanwhile, a developing solution used in the step of subjecting anelectron beam resist of negative type to development can be used also asa peeling solution for that electron beam resist of negative type.However, the above developing solution is expensive and accordingly itsuse also as a peeling solution is not practical. Further, when thedeveloping solution is used also as a peeling solution as mentionedabove, one specific developing solution must be prepared for onespecific electron beam resist of negative type, which not only incurs ahigh cost but also makes the operation complex.

The first object of the present invention is to provide a peelingsolution for photo- or electron beam-sensitive resin which can reliablypeel off various types of photo- or electron beam-sensitive resins fromsubstrates on which said photo- or electron beam-sensitive resins arecoated.

The second object of the present invention is to provide a process forpeeling off a photo- or electron beam-sensitive resin, which canreliably peel off various types of photo- or electron beam-sensitiveresins from substrates on which said photo- or electron beam-sensitveresins are coated and, when said substrates are photomask blanks, canfurther facilitate the removal of the light-shielding films of thephotomask blanks by an etching treatment to be applied after the peelingof photo- or electron beam-sensitive resin.

Other objects of the present invention will be apparent from thefollowing description.

SUMMARY OF THE INVENTION

The present invention has been made in order to achieve the aboveobjects. The peeling solution for photo- or electron beam-sensitiveresin according to the present invention is characterized by consistingof an aqueous solution comprising hydrogen peroxide and a compoundrepresented by the general formula (I) ##STR2## wherein R₁ is H or analkyl group of 1-2 carbon atoms, R₂ is H or an alkyl group of 1-3 carbonatoms, and R₃ is H or an alkyl group of 1-3 carbon atoms.

The process for peeling off a photo- or electron beam-sensitive resinaccording to the present invention is characterized by comprising a stepof treating a photo- or electron beam-sensitive resin-coated substratewith a peeling solution for photo- or electron beam-sensitive resinconsisting of an aqueous solution comprising hydrogen peroxide and acompound represented by the above general formula (I).

DETAILED DESCRIPTION OF THE INVENTION

The present invention is described in detail below.

In the peeling solution for photo- or electron beam-sensitive resinaccording to the present invention, examples of the compound representedby the general formula (I) include the followings. But the compound isnot restricted thereto.

    ______________________________________                                                           R.sub.1                                                                             R.sub.2 R.sub.3                                      ______________________________________                                        (A) Formamides                                                                Formamide            H       H       H                                        N,N-Dimethylformamide (DMF)                                                                        H       CH.sub.3                                                                              CH.sub.3                                 N-Methylformamide    H       H       CH.sub.3                                 N-Ethylformamide     H       H       C.sub.2 H.sub.5                          N-Propylformamide    H       H       C.sub.3 H.sub.7                          N-Methyl N-ethylformamide                                                                          H       CH.sub.3                                                                              C.sub.2 H.sub.5                          N-Methyl N-propylformamide                                                                         H       CH.sub.3                                                                              C.sub.3 H.sub.7                          N,N-Diethylformamide H       C.sub.2 H.sub.5                                                                       C.sub.2 H.sub.5                          N-Ethyl N-propylformamide                                                                          H       C.sub.2 H.sub.5                                                                       C.sub.3 H.sub.7                          N,N-Dipropylformamide                                                                              H       C.sub.3 H.sub.7                                                                       C.sub.3 H.sub.7                          (B) Acetamides                                                                N-Methylacetamide    CH.sub.3                                                                              H       CH.sub.3                                 N-Ethylacetamide     CH.sub.3                                                                              H       C.sub.2 H.sub.5                          N-Propylacetamide    CH.sub.3                                                                              H       C.sub.3 H.sub.7                          N,N-Dimethylacetamide (DMAc)                                                                       CH.sub.3                                                                              CH.sub.3                                                                              CH.sub.3                                 N-Methyl N-ethylacetamide                                                                          CH.sub.3                                                                              CH.sub.3                                                                              C.sub.2 H.sub.5                          N-Methyl N-propylacetamide                                                                         CH.sub.3                                                                              CH.sub.3                                                                              C.sub.3 H.sub.7                          N,N-Diethylacetamide CH.sub.3                                                                              C.sub.2 H.sub.5                                                                       C.sub.2 H.sub.5                          N-Ethyl N-propylacetamide                                                                          CH.sub.3                                                                              C.sub.2 H.sub.5                                                                       C.sub.3 H.sub.7                          N,N-Dipropylacetamide                                                                              CH.sub.3                                                                              C.sub.3 H.sub.7                                                                       C.sub.3 H.sub.7                          (C) Propionamides                                                             N-Methylpropionamide C.sub.2 H.sub.5                                                                       H       CH.sub.3                                 N-Ethylpropionamide  C.sub.2 H.sub.5                                                                       H       C.sub.2 H.sub.5                          N-Propylpropionamide C.sub.2 H.sub.5                                                                       H       C.sub.3 H.sub.7                          N,N-Dimethylpropionamide                                                                           C.sub.2 H.sub.5                                                                       CH.sub.3                                                                              CH.sub.3                                 ______________________________________                                    

The compound of the general formula (I) can be used alone or incombination of two or more.

The ratio of hydrogen peroxide and the compound of the general formula(I) can be various but, to increase the peeling efficiency, ispreferably 100:1 to 10:1 by volume.

The concentrations of hydrogen peroxide and the compound of the generalformula (I) in the peeling solution are preferably 50-700 grams perliter and 1-100 grams per liter, respectively.

The peeling solution can contain other components such as surfactant(e.g. nonylphenol polyoxyethylene ether, dodecylbenzenesulfonic acid,sodium lauryl sulfate), stabilizer (e.g. silicate, stannate, phosphoricacid, pyrophosphate, hydroxyquinoline, acetanilide, barbituric acid,aminotri(methylenephosphonic acid),ethylenediaminetetra(methylenephosphonic acid), 1-hydroxyethylidene1,1-diphosphonic acid, ethylenediaminetetraacetic acid, nitrilotriaceticacid) and the like to such an extent that the required properties of thepeeling solution are not impaired.

The peeling solution of the present invention can be prepared in variousmethods. The peeling solution can be prepared by mixing an aqueoushydrogen peroxide solution with a compound of the general formula (I) oran aqueous solution thereof, or by mixing hydrogen peroxide or anaqueous solution thereof, a compound of the general formula (I) or anaqueous solution thereof, and water. The peeling solution of the presentinvention also includes a kit consisting of an aqueous hydrogen peroxidesolution contained in a given container and a compound of the generalformula (I) or an aqueous solution thereof contained in another givencontainer, both of which are mixed prior to use.

As the photo- or electron beam-sensitive resin which can be peeled offby the peeling solution of the present invention, there can be mentionedelectron beam resists of negative type composed of a polystyrene, anepoxy resin, an unsaturated dicarboxylic acid resin, glycidylmethacrylate-ethyl acrylate copolymer or the like, as well as electronbeam resists of positive type composed of a polyolefinsulfone, apolymethyl methacrylate, methyl acrylate-acrylonitrile copolymer or thelike. Besides these electron beam resists, the photo- or electronbeam-sensitive resin may be various photoresists of negative typecomposed of a polyvinyl cinnamate resin or the like and variousphotoresists of positive type composed of a novolac type phenolic resinor the like.

As the substrate from which a photo- or electron beam-sensitive resin ispeeled off by the peeling solution of the present invention, a photomaskblank is most preferable. The reason is that the peeling solution of thepresent invention not only enables the reliable peeling of photo- orelectron beam-sensitive resin but also facilitates the removal oflight-shielding film from the photomask blank in an etching treatmentafter the peeling of the photo- or electron beam-sensitive resin.

As the light-transmitting substrate of the photomask blank, there can bementioned those composed of silica glass, soda lime glass,aluminoborosilicate glass, aluminosilicate glass, ceramic, sapphire orthe like. As the light-shielding film of the photomask blank, there canbe mentioned those composed of a metal (e.g. titanium, tantalum,tungsten, molybdenum), its oxide, nitride, carbide, silicide or boride,or the like.

The substrate from which a photo- or electron beam-sensitive resin ispeeled off by the peeling solution of the present invention, alsoincludes various other substrates such as a semiconductor substratecomposed of a silicon wafer or the like, a glass substrate composed ofaluminoborosilicate glass or the like, a ceramic substrate composed ofalumina or the like, a substrate consisting of a light-transmittingsubstrate and a transparent condutive film formed on one main surface ofthe light-transmitting substrate, and a resin substrate composed of anacrylic resin or the like. The shape of the substrate is optional andcan be a plate, a cube, etc.

The substrate from which a photo- or electron beam-sensitive resin ispeeled off by the peeling solution of the present invention includes notonly those used in electrical and electronic fields but also those usedin other technological fields.

In order to obtain a peeling efficiency as high as possible, it ispreferable that the peeling solution of the present invention be used ata temperature of 40° C. or above. However, the solution temperature maybe below 40° C. if the peeling power of the solution can be increased bythe proper selection of the ratio of hydrogen peroxide and the compoundof the general formula (I), the type of the compound of the generalformula (I), etc. The solution temperature is preferably 80° C. or abovewhen an electron beam resist of negative type composed of a polystyreneis peeled off. When other electron beam resists of negative type,electron beam resists of positive type and photoresists of positive ornegative type are peeled off, the solution temperature is preferably 40°C. or above.

It is preferable that the peeling treatment be effected by immersing aphoto- or electron beam-sensitive resin-coated substrate in a peelingsolution. The immersion time varies depending upon the peelability ofphoto- or electron beam-sensitive resin or the amount of photo- orelectron beam-sensitive resin coated, but is generally 1-60 minutes.

As the peeling treatment method, there can be adopted, besides the aboveimmersion method, for example, a method of dropping a peeling solutionon a photo- or electron beam-sensitive resin-coated substrate and thenspreading the solution thereon, or a method of spraying a peelingsolution on a photo- or electron beam-sensitive resin-coated substrate.

The present invention is described in more detail below by way ofExamples.

EXAMPLES 1-7

There was used, as a substrate, a photomask blank consisting of (a) alight-transmitting substrate of 5 in.×5 in.×0.09 in. made of polishedsilica glass and (b) a light-shielding film of chromium (film thickness:1,050 Å) formed on one main surface of the light-transmitting substrateby sputtering. On the light-shielding film of the photomask blank wascoated by spin coating, a chloromethylated polystyrene (CMS)manufactured by TOSOH CO., LTD. as a negative type electron beam resistof polystyrene type. The CMS-coated blank was baked for 25 minutes in anatmosphere of 130° C. to prepare a photomask blank having a negativetype electron beam resist film of 5,000 Å in thickness (a blank withnegative type electron beam resist). In this blank with negative typeelectron beam resist, however, the film thickness of the resist wasnon-uniform and it became necessary to peel off the resist.

Hence, a peeling solution for photo- or electron beam-sensitive resin tobe used in Example 1 was prepared by mixing a 34% (by weight ) aqueoushydrogen peroxide solution and N,N-dimethylformamide (hereinafterreferred to as DMF) at a volume ratio of 100/1 and heating the resultingmixture to 80° C. The peeling solution contains 33.7% of hydrogenperoxide and 0.8% of DMF.

Next, peeling solutions for photo- or electron beam-sensitive resin tobe used in Examples 2-6 were prepared in the same manner as in Example 1except that DMF used in Example 1 was replaced by N-ethylformamide,N,N-diethylformamide, N-methylacetamide, N,N-dimethylacetamide(hereinafter referred to as DMAc) and N,N-dimethylpropionamide inExamples 2-6, respectively. Also, a peeling solution for photo- orelectron beam-sensitive resin to be used in Example 7 was prepared inthe same manner as in Example 1 except that DMF used in Example 1 wasreplaced by a mixture of DMF and DMAc (volume ratio: 0.5/0.5). Thecompositions of the above prepared peeling solutions of Examples 1-7 areshown in Table 1.

Then, the above blank with negative type electron beam resist wasimmersed in each of the peeling solutions of Examples 1-7 (solutiontemperature: 80° C.) for a given length of time (10 minutes in Examples1-5 and 7 and 20 minutes in Example 6) to peel off the negative typeelectron beam resist from the surface of the light-shielding film.Thereafter, each blank was rinsed with tap water and dried. Upon visualobservation of the surface of the light-shielding film of each photomaskblank, the resist had been satisfactorily peeled off and removed in eachblank.

Each of the above photomask blanks from which the negative type electronbeam resist had been peeled off was then immersed in an specific etchingsolution for chromium light-shielding film (solution temperature: 20°C.) obtained by dissolving 200 g of ceric nitrate ammonium and 50 ml ofperchloric acid in one liter of pure water, and a time required for theremoval of the chromium light-shielding film was measured. The time was60 seconds in all cases, as shown in Table 1. Incidentally, the removalby the same etching solution, of the chromium light-shielding film fromthe above prepared photomask blank without the formation of the negativetype electron beam resist film thereon required the same 60 seconds.Therefore, it was confirmed that no thin film of negative type electronbeam resist remained on the surface of the light-shielding film of eachphotomask blank from which the negative type electron beam resist hadbeen peeled off, and consequently the removal of the light-shieldingfilm was not hindered.

COMPARATIVE EXAMPLES 1-4

As a comparative peeling solution for photo- or electron beam-sensitiveresin, there were used methyl ethyl ketone (hereinafter referred to asMEK) in Comparative Example 1, hot concentrated sulfuric acid inComparative Example 2, dimethyl sulfoxide in Comparative Example 3 and amixed solution of acetone and DMF in Comparative Example 4. The sameblank with negative type electron beam resist as used in Examples 1-7was immersed in each of the above peeling solutions at giventemperatures for given lengths of time shown in Table 1 in order to peeloff the resist. As a result, it was clear by visual observation that theresist was apparently peeled off and removed in Comparative Examples 1,2 and 4 which used, as the peeling solution, MEK, hot concentratedsulfuric acid and a mixed solution of acetone and DMF, respectively, butin Comparative Example 3 which used dimethyl sulfoxide as the peelingsolution, the resist could not be peeled and removed even after 10 hoursof immersion in peeling solution at 100° C.

Next, the rinsing and drying treatments were effected in the same manneras in Examples 1-7. Then, each of the resulting photomask blanks weretreated with the same etching solution as used in Examples 1-7, and thetime required for the removal of the chromium light-shielding film ofeach photomask blank was measured. The results are shown in Table 1. InComparative Example 2 which used hot concentrated sulfuric acid as thepeeling solution, more than 5 hours was required for the removal ofchromium light-shielding film; in Comparative Examples 1 and 4 whichused MEK and a mixed solution of acetone and DMF, respectively, thechromium light-shielding film could not bc removed. The reason for theabove (taking a long time to remove the chromium light-shielding film orbeing impossible to remove it) is that the resist appeared to eyes tohave been peeled off but actually the resist remained on the surface ofthe chromium light-shielding film as a thin film of negative typeelectron beam resist and hindered the removal of the light-shieldingfilm.

                                      TABLE 1                                     __________________________________________________________________________                                    Immersion in                                                                            Time required for removal                                           peeling solution                                                                        of chromium light-                         Composition of peeling solution.sup.(1)                                                                Temp.                                                                              Time shielding film                      __________________________________________________________________________    Example                                                                       1      34 wt. % H.sub.2 O.sub.2 /DMF = 100/1                                                                  80° C.                                                                      10                                                                              min                                                                              60 sec                              2      34 wt. % H.sub.2 O.sub.2 /N-ethylformamide = 100/1                                                     80° C.                                                                      10                                                                              min                                                                              60 sec                              3      34 wt. % H.sub.2 O.sub.2 /N,N-diethylformamide = 100/1                                                 80° C.                                                                      10                                                                              min                                                                              60 sec                              4      34 wt. % H.sub.2 O.sub.2 /N-methylacetamide = 100/1                                                    80° C.                                                                      10                                                                              min                                                                              60 sec                              5      34 wt. % H.sub.2 O.sub.2 /DMAc = 100/1                                                                 80° C.                                                                      10                                                                              min                                                                              60 sec                              6      34 wt. % H.sub.2 O.sub.2 /N,N-dimethylpropionamide                                                     80° C.                                                                      20                                                                              min                                                                              60 sec                              7      34 wt. % H.sub.2 O.sub.2 /DMF/DMAc = 100/0.5/0.5                                                       80° C.                                                                      10                                                                              min                                                                              60 sec                              Comparative                                                                   Example                                                                       1      MEK                      20° C.                                                                      12                                                                              hr Film unremovable.                   2      Hot concentrated sulfuric acid                                                                         90° C.                                                                      5 min                                                                              More than 5 hr.                     3      Dimethyl sulfoxide       100° C.                                                                     10                                                                              hr Not measured because                                                          resist did not peel.                4      Mixed solution of acetone and DMF                                                                      25° C.                                                                      3 min                                                                              Film unremovable.                   __________________________________________________________________________     .sup.(1) Ratio of components in peeling solution is volume ratio.        

The same blank as in Examples 1-7 was used as a substrate. On thelight-shielding film of the blank was coated, by spin coating, apolybutene-1-sulfone (PBS) as a positive type electron beam resist ofpolyolefinsulfone type. The PBS-coated blank was baked for 60 minutes inan atmosphere of 120° C. to prepare a photomask blank having a positivetype electron beam resist film of 4,000 Å in thickness (a blank withpositive type electron beam resist).

In this blank with positive type electron beam resist, however, the filmthickness of the resist was non-uniform and it became necessary to peeloff the resist.

Hence, in Examples 8-14, the peeling of the resist from the blank withpositive type electron beam resist was effected as follows using thesame peeling solutions as in Examples 1-7 (the same peeling solutions asused in Examples 1-7 were used in Examples 8-14, respectively).

That is, the blank with positive type electron beam resist was immersedin each of 7 peeling solutions of Examples 8-14(maintained at 80° C.)for a given length of time (3 minutes in Examples 8-12 and 14 and 6minutes in Example 13) to peel off the positive type electron beamresist from the surface of the light-shielding film. Thereafter, eachblank was rinsed with tap water and dried. Upon visual observation ofthe surface of the light-shielding film of each photomask blank, theresist had been satisfactorily peeled off and removed in each blank.

Each of the above photomask blanks from which the positive type electronbeam resist had been peeled off was then immersed in the same etchingsolution as used in Examples 1-7, and a time required for the removal ofthe chromium light-shielding film was measured. The time was 60 secondsin all cases, as shown in Table 2. For the same reasons as described inExamples 1-7, it was confirmed that no thin film of positive typeelectron beam resist remained on the surface of the light-shielding filmof each photomask blank from which the positive type electron beamresist had been peeled off.

                                      TABLE 2                                     __________________________________________________________________________                                  Immersion in                                                                          Time required for removal                                             peeling solution                                                                      of chromium light-                      Composition of peeling solution.sup.(1)                                                                     Temp.                                                                             Time                                                                              shielding film                          __________________________________________________________________________    Example                                                                        8   34 wt. % H.sub.2 O.sub.2 /DMF = 100/1                                                                  80° C.                                                                     3 min                                                                             60 sec                                   9   34 wt. % H.sub.2 O.sub.2 /N-ethylformamide = 100/1                                                     80° C.                                                                     3 min                                                                             60 sec                                  10   34 wt. % H.sub.2 O.sub.2 /N,N-diethylformamide = 100/1                                                 80° C.                                                                     3 min                                                                             60 sec                                  11   34 wt. % H.sub.2 O.sub.2 /N-methylacetamide = 100/1                                                    80° C.                                                                     3 min                                                                             60 sec                                  12   34 wt. % H.sub.2 O.sub.2 /DMAc = 100/1                                                                 80° C.                                                                     3 min                                                                             60 sec                                  13   34 wt. % H.sub.2 O.sub.2 /N,N-dimethylpropionamide                                                     80° C.                                                                     6 min                                                                             60 sec                                  14   34 wt. % H.sub.2 O.sub.2 /DMF/DMAc = 100/0.5/0.5                                                       80° C.                                                                     3 min                                                                             60 sec                                  __________________________________________________________________________     .sup.(1) Ratio of components in peeling solution is volume ratio.        

EXAMPLE 15

In this Example, the peeling solution for photo- or electronbeam-sensitive resin of the present invention was examined for thechange of peeling power with time.

First, 6 blanks with positive type electron beam resist (5 in.×5in.×0.09 in.), all of which were the same as used in Examples 8-14, wereeach cut along the center line parallel to the opposing two fringelines, into two pieces with a glass cutter to prepare 12 test samples (5in.×2.5 in.×0.09 in.). As mentioned below, 11 of these test samples wereused in this Example.

Then, a 35 wt. % aqueous hydrogen peroxide solution (0.5 liter) and DMAcwere mixed at a volume ratio of 100/1 and heated to 80° C. to prepare apeeling solution having the same composition as used in Example 12. Thepeeling solution was measured for initial concentration of hydrogenperoxide according to the potassium permanganate titration methodspecified by JIS (Japanese Industrial Standard) K 8230. The initialhydrogen peroxide concentration was 35.0% by weight as shown in Table 3.

After the peeling solution had been kept at 80° C. for 1 hour, one ofthe test samples was added to the solution and immersed therein for 10minutes. After 10 minutes of the immersion, the positive type electronbeam resist of the test sample was satisfactorily peeled off from thesurface of the light-shielding film and no thin resist film remainedthereon. The hydrogen peroxide concentration after 10 minutes of theimmersion was 35.2% as shown in Table 3, which was almost same as theinitial concentration.

Next, there was measured hydrogen peroxide concentrations after thepeeling solution had been kept at 80° C. for 2 and 3 hours. They were35.1% and 35.0%, respectively, as shown in Table 3 and were almost sameas the initial concentration.

From 3.5 hours to 8 hours after the preparation of the peeling solution,each one test sample was added to the peeling solution at intervals of0.5 hour and immersed therein for 10 minutes. After 10 minutes of eachimmersion, the positive type electron beam resist of each test samplewas satisfactorily peeled off from the surface of the light-shieldingfilm and no thin resist film remained thereon. The hydrogen peroxideconcentrations after 10 minutes of the imersion showed only very slightreduction from 3.5 hours to 8 hours as shown in Table 3. Thus, thepeeling solution of the present invention was found to have good peelingpower after 8 hours.

                                      TABLE 3                                     __________________________________________________________________________              Time from the production of peeling solution, (hr)                            0  1.0 2.0                                                                              3.0                                                                              3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0                __________________________________________________________________________    Immersion of test                                                                       No Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes                sample                                                                        Peeling of resist                                                                       -- Good                                                                              -- -- Good                                                                              Good                                                                              Good                                                                              Good                                                                              Good                                                                              Good                                                                              Good                                                                              Good                                                                              Good                                                                              Good               H.sub.2 O.sub.2 concentra-                                                              35.0                                                                             35.2                                                                              35.1                                                                             35.0                                                                             34.8                                                                              34.9                                                                              34.9                                                                              34.7                                                                              34.6                                                                              33.7                                                                              33.5                                                                              33.4                                                                              33.1                                                                              32.9               tion*.sup.1, (wt. %)                                                          __________________________________________________________________________     *.sup.1 The H.sub.2 O.sub.2 concentration when a test sample was immersed     is a H.sub.2 O.sub.2 concentration after 10 minutes of the immersion.    

The change of peeling power with time was examined also on peelingsolutions having the same compositions as in Examples and 14, in thesame manner as in Example 15. The results were similar to that ofExample 15. As is clear from the above, the peeling solution for photo-or electron beam-sensitive resin according to the present inventionretains good peeling power even after an elapse of a long time from thepreparation or even after the use for a long time, and can reliably peeloff photo- or electron beam-sensitive resins.

In Example 15, the change of peeling power with time was examined usinga blank coated with a positive type electron beam resist composed ofpolybutene-1-sulfone as photo- or electron beam-sensitive resin. Thispositive type electron beam resist composed of polubutene-1-sulfone, ascompared with a negative type electron beam resist composed ofchloromethylated polystyrene, easily dissolves in a peeling solutionand, by the help of the dissolution, is peeled off and removed from thephotomask blank. Meanwhile, the negative type electron beam resistcomposed of chloromethylated polystyrene is peeled off from thephotomask blank as if the bark is peeled off from a tree. Therefore,when the positive type electron beam resist composed ofpolybutene-1-sulfone is treated with the peeling solution of the presentinvention, the hydrogen peroxide concentration in peeling solution ismore affected because the resist dissolves in the peeling solution tocause a reaction therewith. In view of this matter, it can be said thatthe peeling solution of Example 15 retains better peeling power for thenegative type electron beam resist composed of chloromethylatedpolystyrene than for the positive type electron beam resist composed ofpolybutene-1-sulfone, even after an elapse of a long time.

In Example 15, the immersion time was set at 10 minutes which was longerthan 3 minutes in Example 12 using the same peeling solution. Thislonger immersion time was selected in order to examine whether or notthe peeling solution still retained sufficient peeling power even if thepeeling solution had reacted with the chromium light-shielding filmexposed as the result of peeling of the resist and thereby the hydrogenperoxide concentration in peeling solution had been reduced.

As described above, the peeling solution for photo- or electronbeam-sensitive resin according to the present invention can peel offphoto- or electron beam-sensitive resins reliably in a short time andcan retain good peeling power for a long time.

The process for peeling off a photo- or electron beam-sensitive resinaccording to the present invention can peel off photo- or electronbeam-sensitive resins coated on substrates reliably in a short time.

Further, when said substrates are photomask blanks, the process forpeeling off a photo- or electron beam-sensitive resin according to thepresent invention can peel off photo- or electron beam-sensitive resinscoated on the blanks reliably in a short time and can facilitate theremoval of the light-shielding film of the blank by the subsequentetching treatment.

What is claimed is:
 1. A process for peeling off a photo- or electronbeam-sensitive resin, which comprises a step of treating a photo- orelectron beam-sensitive resin-coated substrate with a peeling solutionfor photo- or electron beam-sensitive resin consisting of an aqueoussolution consisting of hydrogen peroxide and at least one compoundrepresented by the general formula (I) ##STR3## wherein R₁ is H or analkyl group of 1-2 carbon atoms, R₂ is H or an alkyl group of 1-3 carbonatoms, and R₃ is H or an alkyl group of 1-3 carbon atoms.
 2. A processfor peeling off a photo- or electron beam-sensitive resin according toclaim 1, wherein the compound of the general formula (I) is at least onemember selected from the group consisting of formamides, acetamides andpropionamides.
 3. A process for peeling off a photo- or electronbeam-sensitive resin according to claim 2, wherein the formamides are atleast one member selected from the group consisting of formamide,N,N-dimethylformamide, N-methylformamide, N-ethylformamide,N-propylformamide, N-methyl N-ethylformamide, N-methylN-propylformamide, N,N-diethylformamide, N-ethyl N-propylformamide andN,N-dipropylformamide.
 4. A process for peeling off a photo- or electronbeam-sensitive resin according to claim 2, wherein the acetamides are atleast one member selected from the group consisting ofN-methylacetamide, N-ethylacetamide, N-propylacetamide,N,N-dimethylacetamide, N-methyl N-ethylacetamide, N-methylN-propylacetamide, N,N-diethylacetamide, N-ethyl N-propylacetamide andN,N-dipropylacetamide.
 5. A process for peeling off a photo- or electronbeam-sensitive resin according to claim 2, wherein the propionamides areat least one member selected from the group consisting ofN-methylpropionamide, N-ethylpropionamide, N-propylpropionamide andN,N-dimethylpropionamide.
 6. A process for peeling off a photo- orelectron beam-sensitive resin according to claim 1, wherein the photo-or electron beam-sensitive resin to be peeled off is an electron beamresist of negative or positive type.
 7. A process for peeling off aphoto- or electron beam-sensitive resin according to claim 1, whereinthe substrate is a photomask blank consisting of a light-transmittingsubstrate and a light-shielding film formed on one main surface of thelight-transmitting substrate.
 8. A process for peeling off a photo- orelectron beam-sensitive resin according to claim 1, wherein thetreatment is effected by immersing the photo- or electron beam-sensitiveresin coated substrate in the peeling solution for photo- or electronbeam-sensitive resin.
 9. A process for peeling off a photo- or electronbeam-sensitive resin according to claim 1, wherein the temperature ofthe peeling solution is kept at 40° C. or higher.